Steam generator



M. H. KUHNER STEAM GENERATOR Filed Jan. 27, 1937 4 MAX hi K UHNER May 16, 1939.

/l //////U///W/ Patented May 16, 1939 UNITED STATES PATENT OFFICE STEAM GENERATOR Application January 27, 1937, Serial No. 122518 2 Claims.

This invention relates to steam generators, and more particularly to steam generators of the water tube type having means for superheating the steam which is generated in the water tubes.

With steam generators as ordinarily constructed there is usually a considerable variation in the temperature of the superheated steam as the demand for steam varies. This has been recognized heretofore, and many different arrangements have been proposed for controlling the flow of the hot gases over the superheater and thus regulating the steam temperature.

The main object of the present invention is to improve upon these prior arrangements and to provide a steam generator of a comparatively simple and inexpensive Construction which will be eective to deliver superheated steam at high rates and with accurate control of the temperature of the steam.

A further object of the invention is to provide a steam generator having comparatively simple means for controlling the temperature of the steam, and to avoid pockets in which soot and fly-ash may accumulate in the gas passages.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is a longitudinal section through a steam generator; and

Fig. 2 is an enlarged ragmentary view in section on the line 2-2 of Fig 1.

The embodiment illustrated comprises an upper rear transverse steam-and-water drum !0, a lower rear transverse water drum l! therebeneath, and a front transverse water drum or header !2 located at a height somewhat lower than that of the drum !9. A bank of upright water tubes !4 extends between the drums and H, and three rows of water tubes !5 extend between the drums !0 and !2, the uppermost row of the tubes !5 forming a support for a roof !6 of refractory material. The drums !l and !2 are connected by two rows of water tubes !8 and by a third row of water tubes !9. The tubes !8 0 and !9, after leaving the rear water drum Il,

extend substantially vertically upward for a substantial distance and then forwardly at a slight upward inclination to the front drum !2. The inclined portions of the tubes !9 are shown spaced well above the corresponding portions of the tubes !8 therebeneath. The various parts so far described are mounted within a setting comprising a front wall ZI, side walls 22 and a rear wall 23. These Walls enclose a combustion chamber 25 located beneath the tubes !8.

A baffle 2'! extends upwardly from the rear water drum l! in the rear of the tubes !9, and terminates some distance below the steam-andwater drum !0. With this Construction the hot gases flow upwardly from the combusticn chamher 25, past the tubes !8 and !9, and rearwardly ever the top of the baffle 2'! into contact with the upper portion of the tube bank !4. 'I'hence the gases flow downwardly to a gas outlet 28 near the rear water drum ll, bafiles 29 being pro vided in the rear of the bame 2'! to direct the downwardly fiowing gases back and forth across the tubes !4.

A superheater 3! is mounted in the space between the tubes !5 and the tubes !9, and connected to the steam-and-water drum !9 to receive steam therefrom. This superheater comprises a series of parallel tubes, each bent into a sinuous form, With long straight portions connected by loops to provide a large surface area. The straight portions of these superheater tubes are substantially parallel to the Water tubes !9. The superheater 3! delivers steam to a header 33 located above the roof !6, and from this header the steam fiows to a second superheater 35 located in the space between the tubes !8 and !9. This second superheater is of substantially the same Construction as the first superheater, but has considerably less surface area. From the second superheater the steam flows to an outlet header 3'! located adjacent the header 33 In order to control the flow of the hot gases over the superheating surface and thus make possible a regulation of the temperature of the superheated steam, an upright baffle 39 is provided across the superheater 3! intermediate the length thereof. This baffle divides the upwardly fiowing gas into two streams, one stream contacting with the rear portion of the superheater and the other stream contacting with the front portion of the superheater. The bame 39 is preferably of monolithic Construction, and it may be supported and cooled by means of a row of water tubes 40. These tubes extend upwardly from the drum I! directly in the rear of the baffie 21, d

preferably formed in a plurality of sections located between the tubes 40. The damper sections are Secured to a horizontal shaft 43 rotatably supported in bearings 44 carried by the tubes 48. This shaft extends outwardly through a scaling ring 45 in one side Wall 22, so that it can be actuated manually or by means of any suitable and well-known automatic* mechanism (not shown) responsive to the temperature of the steam delivered to the header 31.

It will now be apparent that with the damper 42 closed, as shown in Fig. 1, most of the gases from the combustion chamber 25 will be compelled to flow upwardly in the rear of the superheater bafile 39. However, this is the more direct path for the gases even with the damper 42 open, and in order to utilize the full superheater surface under these conditions there is preferably provided a perforated or filter baffie ll beneath the rear portion of the superheater. This bafiie H may be iormed by means of tile supported on the tubes IS between the bales ?i and 39, these tile being spaced apart or otherwise arranged to provide openings 48 through which the gases may flow.

The operation of the invention will now be apparent from the above disclosure. Any suitable fuel is burned in the combustion chamber 25, and the hot gaseous products of combustion flow up- Wardly past the water tubes it, the superheater 35, the water tubes IS, the superheater 39, and thence downwardly into contact with the tube bank l4 to the outlet 28. Steam generated in the various water tubes passes into the drum li whence it flows through the superheaters 3! and 35 in a generally downward direction in counterflow relation with the hot gases and thence to the outlet header 37. If the temperature of the superheated steam becomes higher than that desired, the damper 42 will be moved toward the closed position shown in Fig. 1, whereupon more of the gases will be compelled to flow upwardly through the filter baffle 47 and into contact with the rear portion of the superheater si. Thus the front portion of the superheater Bi will be rendered less effective, and as a result the steam temperature will be lower-ed.. In case the steam temperature becomes lower than that desired, the damper 52 will be moved toward the open position, whereupon the flow of gases into contact with the front portion of the superheater will be increased and the steam temperature will be raised. With the damper 42 fully open the entire area of the superheater will be effective, since the resistance set up by the filter battle 47 will cause a considerable proportion of the gases to travel through the less direct path around the front of the battle 39, while the battle openings 48 will at the same time allow a substantial gas flow through the more direct path in the rear of the bafile 39. The surface area of the superheater 35 is for the most part effective whatever the adjustment of the damper, since it will be rather completely swept by the gases even with the damper closed. Moreover, this superheater 35 is subjected to considerable racliant heat from the combustion chamber 25. The entire Construction is comparatively simple and inexpensive, and the available space is fully utilized. The b-afiie Construction is such that no great quantities of soot or fiy-ash can accumulate thereon, since all pockets and large horizontal surfaces are avoided.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A steam generator comprising a transverse steam-and-water drum, a transverse water drum therebeneath, a bank of upright water tubes connecting the drums, a superheater in front of the water tubes, the superheater having a front portion remo'te from the water tubes and a rear portion adjacent to the water tubes, a combustion chamber beneath the superheater, means to direct hot gases from the combustion chamber upwardly into contact with the superheater and thence rearwardly into contact with the water tubes, a transverse bafe dividing the gases into two separate streams which contact with the front and rear portions of the superheater respectively, a filter baffle located beneath the rear portion of the superheater to restrict the flow in the rear stream, a row of water tubes extending upwardly from the water drum and forming a support for ile filter baflle. and an adjustable damper located above the transverse baffie to control the flow in the forward stream.

2. A steam generator comprising a rear transverse steam-and-water drum, a rear transverse water drum therebeneath, a bank o-f upright water tubes connecting the drums, a superheater in front of the upper portion of the tube bank and including a series of tubes each bent into a sinuous form with long straight portions connected by loops, the straight portions extending at a slight downward incline toward the rear, means to supply steam from the steam-and-water drum to the superheater for flow through the sinuous tubes in a generaliy downward direction, a combustion chamber beneath the superheater and so arranged with relationship thereto as to cause the hot gases to flow directly upwardly from the combustion chamber and past the superheater in counterflow relation with the steam, an upright baflle extending transversely of the superheater intermediate the lengths of the straight portions thereof to divide the upwardly fiowing gases into front and rear streams which unite as they leave the superheater, a filter baflle located beneath the rear portion of the superheater to restrict the flow in the rear gas stream, an adjustable damper mounted above the upright baiile in a position to control the flow in the front gas stream, and means to direct the united stream of gas into contact with the tube bank while flowing in a generally downward direction.

MAX I-I. KUHNER. 

